I agree that Rowling "stole" from Tolkien and I imagine other writers works. That or she had a similar idea, and had never even thought that they were... ah... related, I guess you could say. Example: Tolkien's Nazgul, Rowling's Dementors, and Jordan's Fades. All wear black robes, and seem to have close to the same affect on people. I don't know about you, but if I were writing a story and I wanted a rather scary enemy, I would probably make them the same way. I have been tempted to do so before, but have felt that the idea is going to be a bit overused in the future.
Though I love Tolkien's works, I find HP and WoT amusing also. Even if they did "steal" from our favorite author. I have found that when I am writing, I come to a place where I think,
That line in FotR would go great right here. Not because I am a theif. It is because of my great love for Tolkien. If ever I become a writer, I will be sure to state that many of my ideas came from Tolkien and that I owe everything to him for getting me interested in writing in the first place.